An American service member was believed to be in North Korean custody on Wednesday after willingly crossing into the nuclear-armed country, despite a by the U.S. State Department due to the risk of arrest and long-term detention.

But the service member, Travis King, was far from the first U.S. national to venture into or be detained by the reclusive country.

Numerous U.S. citizens ¡ª including soldiers, tourists, journalists and scholars ¡ª have been detained or crossed into North Korea since the Cold War.